Up to 20 provinces across the country are likely to experience drought in the dry season, Deputy Prime Minister Chatchai Sarikulya warned on Monday.
The issue was raised again after authorities earlier last month expressed concern over insufficient water levels in many dams for irrigating farmland during the coming cool season.
After these mild months, the country will be hit by the heat of summer, which will accentuate the water scarcity, Gen Chatchai said.
There are 20 provinces that have been listed for greater care because some places there still do not have piped tap water provided by the Provincial Waterworks Authority, Gen Chatchai said on Monday after a meeting on water management plans for next year.
These places are in parts of Chiang Mai, Sukhothai, Phetchabun, Uthai Thani, Nakhon Sawan, Suphan Buri, Chai Nat, Ang Thong, Sing Buri and Kanchanaburi.
Other areas are in Ratchaburi, Samut Songkhram, Chaiyaphum, Maha Sarakham, Khon Kaen, Loei, Roi Et, Surin, Buri Ram and Nakhon Ratchasima.
The Department of Groundwater Resources has been told to step up efforts to build artesian wells for residents in these areas.
"We expect to build 338 by the end of the year," Gen Chatchai said.
"Even in areas where a piped water network has been installed, people are still required to use water carefully," he added.
Banchong Thepkasetkun, manager of Buri Ram Provincial Waterworks Authority, on Monday asked residents in Muang district and parts of Huai Rat district to "save water to avoid future shortages".
The two districts depend on tap water supplied mainly from Huai Chakhemak reservoir. It is among 16 reservoirs in this lower northeastern province which are currently holding less water than in previous years. At present, there are only 2.1 million cubic metres of water in Huai Chakhemak, which is much lower than its capacity of 26 million cu/m.
This means officials must carefully plan how to sufficiently distribute water to 28,700 residents in the two districts during the dry season who use about 1.5 million cu/m of tap water on average each month.
One measure is to reduce piped water pressure from 3 to 2.5 bars. The reduction will be applied between 9.30pm and 5.30am.
"This should reduce water use by about 200,000 cu/m a day," Mr Banchong said.
His agency has also spent 10 million baht on a plan to divert 100,000 cu/m of water a day from the Mat River to Huai Chakhemak, he said. The money is needed to cover the cost of electricity used by the pumping machinery.
Meanwhile, farmers in areas where drought is looming have been told not to plant rice in the dry season.
"They can grow crops like maize and beans that require less water or shift to other careers including selling handcrafts," Gen Chatchai said.
The need to manage water quality is also crucial, the deputy prime minister added, reasoning that a healthy ecosystem requires water that is free from toxins.
Officials were on Monday told to protect major rivers, including the Chao Phraya and Tha Chin rivers, against pollutants.